The present invention relates to apparatus and methods for sensing mass flow of a fluid along a flow path and particularly relates to a mass flow sensor using a bluff body in the flow path to determine fluid density and velocity and thereby the mass flow rate in a given flow passage.
In industrial process control, it is often necessary to determine the mass flow rate of fluids along flow paths, e.g. pipes. There are a number of known sensors which provide mass flow rate. For example, one sensor is based on the coriolis principle. Coriolis mass flow meters are generally considered to be highly accurate. However they do have limitations. One such limitation is that they may cause excessive pressure drop in the fluid flow, when sized smaller than adjacent piping to speed up a flow that would otherwise be too low to be readily measured. Other limitations include substantial expense for large sizes of Coriolis flow meters as well as inaccurate or erratic performance if the fluid contains entrained gases. Also not all Coriolis based mass flow meters, as well as other flow meters, can be applied in practical mounting configurations, for example, one particular measuring device generally is not usable in pipes of substantially different sizes. Nor can conventional mass flow sensors provide the accuracy, bidirectionality, ease of installation and economics necessary for a commercial mass flow sensor.